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Electrochemical investigation of MoSeTe as an anode for sodium-ion batteries

Sodium ion batteries (SIBs) are considered as an efficient alternative for lithium-ion batteries (LIBs) owing to the natural abundance and low cost of sodium than lithium. In this context, the anode materials play a vital role in rechargeable batteries to acquire high energy and power density. In order to demonstrate transition metal dichalcogenide (TMD) as potential anode materials, we have synthesized MoSeTe sample by conventional flux method, and the structure and morphology are characterized using x-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and Raman spectroscopy. These characterisations confirm the hexagonal crystal symmetry with p63/mmc space group and layered morphology of MoSeTe. We investigate the electrochemical performance of a MoSeTe as a negative electrode (anode) for SIBs in the working potential range of 0.01 to 3.0~V. In a half-cell configuration, the MoSeTe as an anode and Na metal as counter/reference electrode exhibits significant initial specific discharge capacities of around 475 and 355 mAhg$^{-1}$ at current densities of 50 and 100 mAg$^{-1}$, respectively. However, the capacity degraded significantly like $\approx$200~mAhg$^{-1}$ in 2nd cycle, but having $\approx$100\% Coulombic efficiency, which suggest for further modification in this material to improve its stability. The cyclic voltammetry (CV) study reveals the reversibility of the material after 1st cycle, resulting no change in the initial peak positions. The electrochemical impedance spectroscopy (EIS) measurements affirms the smaller charge transfer resistance of fresh cells than the cells after 10th cycle. Moreover, the extracted diffusion coefficient is found to be of the order of 10$^{-14}$ cm$^2$s$^{-1}$.